Pneumatic carrier systems for the distribution and transport of materials may connect a multitude of locations, any of which may be the initial source or ultimate destination of a particular carrier. The pneumatic tubes which connect these locations, or stations, may be arranged in a manner which permits carriers from various source stations to pass through a particular section of a pneumatic tube. When the paths of two of the carriers conflict, a gridlock condition may occur, which does not permit either carrier to proceed. Another form of gridlock occurs when a number of carriers become stalemated and unable to move forward due to the presence of the other carriers in the system.
One method of avoiding gridlock is to reserve all of the sections of tube which are necessary for the path of a particular carrier from its source to its destination until the complete path has been traversed. However, this method of avoiding gridlock is inefficient, as it causes all sections of tube in the path, other than the instant location of the carrier, to be idle until the carrier has completed the entire reserved path. As a result, a large portion of the system may be idle at any one time, resulting in inefficiency.